Media, process for the representation of figures, designs, drawings, etc., thereon and method of making said media



Dec. 10, 1940. M D. McxNTosH 2,224,654 MEDIA,YPROCESS FOR THE REPRESENTATION OF FIGURES, DESIGNS, DRAWINGS,

ETC., THEREON AND METHOD OF MAKING SAID MEDIA Filed Dec. l, 1938 I I I I l O I I I I I MIIIIIIIIII'IIIIIIIW .\\\\\\\\\\\\\\\\\\\\\\\v/ /E /r/GG MQUP/CE D 79 /NTosf-r /Nl/EN TOR @Tv-oever Patented Dec. l0, 1940 UNITED STATES PATENT OFFICE SAID MEDIA Maurice n. McIntosh, cleveland, omo, signor to Louis S. Sanders, Cleveland, Ohio Application December 1, 1938, Serial No.` 243,420,

20 Claims.

This invention relates to media upon which figures, designs, drawing, and the like may be depicted and to the method of making said media.

In my pending application', Serial No. 178,105, I have disclosed a basically novel medium and a basically novel mode of representing ilgures. designs, drawings, and the like upon said medium whereby said figures, designs, drawings and the like may be produced not only in solid blacks and whites but also in any and all gradations of tone values between black and white, and are directly suitable for camera copy and for direct reproduction as line photo-engraving without resorting to the expensive halftone process heretofore required in reproduction of continuous tone copy. My present invention embraces improvements upon the invention disclosed in my said application. By virtue of my instant invention I am able to secure the highly advantageous results obtained by my former invention through the agency of improved media. These media greatly facilitate theV representation of iigures, designs. drawings, and the like and-the methods of their production achieve economies in time and cost. 'I'hey are better able to take pencil, crayon, and ink lines and present a superior integration of the constituent elements of which they are composed. Dots, lines, areas or other units when developed upon my improved media are of a more intense black and more highly resistant to light, heat and oxidation.

My invention encompasses, moreover, improvements in the chemical development of figures upon my media. These improvements are conducive to substantial savings in time and facilitate the ease and certaintywith which the media may be employed. A uniform development of light tone areas and a more rapid' development of darker tone areas are secured. The solution utilized for the development of the darker tone areas is colored so that the areas to which it is applied are sharply dened. Where a brush is used for application of the developer the artist is thus enabled to follow his brush strokes with greater ease and precision especially over previously developed areas.

'I'he main object of my invention resides, therefore, in the provision of improved media for the representation of gul'eadesigns, drawings, and the like, proceeding from white or other actinic color through all sequences of half tones toA solid black or other non-actinic color which media shall be suitable for camera copy and the production of line photo-engravings without resorting to the half tone process.

Further objects are the provision` of novel methods of preparing such media and the novel mode of representing gures, designs, drawings andthe like upon media in the production of camera copy including all gradations of tone values without resorting to the half tone process.

Other objects of the invention will become clear from the foregoing general statement of my invention and from the following detailed description thereof.

In the drawing forming part of this specification:

Fig. 1 is a fragmentary perspective view of one y of my novel media, portions of the constituent elements being broken away for greater clarity.

y Fig. 2 is a section of the medium shown inl Fig. l.

Fig. 3 is a fragmentary plan view of the medium of Fig. 1 showing the application of a developer thereto.

Fig. 4 is a view similar to Fig. 3 showing the application of a second developer over previously developed areas.

Fig. 5 is a view similar to Fig. 1 vshowing a second medium.

Fig. 6 is a view similar to Fig. 3 showing the designs, drawings and the like in such manner 35 that any desired range of tone values may be produced. The medium illustrated in these views embodies the paper stock i0 which may be hard sized white drawing board or pa'per. To this sheet I apply a thin fllm of sensitized gelatin. Albumen, casein, glue, and the like may be used in place of gelatin. The sensitive agent which I employ is mercurous chloride and in accordance with my invention such agent is carried in suspension in the gelatin. I am thus enabled to apply the gelatin film and sensitlzer in one operation.

In the production of my gelatin-mercurous chloride colloid solution I prepare a solution of 950 parts of water, 113 parts of gelatin (dry, purified) and 11 parts of sodium chloride, which for easy reference I designate as solution No. 1. The parts stated are by weight. 'I'he gelatin is soaked in the water, preferably cold, for about an hour. The sodium chloride is then added and the solution is heated until all the gelatin and salt are dissolved. For the proportions and time element given I have found that the heating temperature should not exceed 140 F. However, I do not wish to limit myself to this temperature or precisely to the stated proportions of the in gredlents since it will be apparent that these may be varied. These factors are controlled by the occurrence of decomposition of the gelatin which is to be avoided. I have found that when the heating temperature does not exceed 140 F.

decomposition of the stated solution is prohibited and a satisfactory solution is secured.

A solution, designated solution No. 2, is prepared. To 300 parts of water I add 2 parts of nitric acid (HNOa, sp. gr. 1.42) and l part of metallic mercury. I then add 35 parts of mer- 'aurous nitrate (HgNOa.2H2O). All parts are by weight. These ingredients are then heated to notover 170 F. until all the mercurcus nitrate is dissolved. I have found that if the heating temperature exceeds 170 F. decomposition of the mercurous nitrate occurs which is to 'be avoided. 'I'his decomposition is the limiting factor involved.

To obtain the colloidal suspension of mercurous chloride in the gelatin I mix solutions Nos. 1 and 2 at a temperature of 130 F., which while not critical I have found to be satisfactory. Solution No. 2 is poured very slowly into solution No. l accompanied by vigorous stirring. Mercurous chloride is precipitated in colloidal condition in the gelatin solution. Vigorous stirring is desirable since it eilects a finer suspension of the mercurous chloride. Mechanical stirring is therefore preferred and may be accomplished by a number of mechanical-mixers available in the market.

When the mixture of the No. 1 and No. 2 solutions has cooled sufficiently, preferably to about 100 F. I add a solution designated as solution No. 3. In preparing this solution I dissolve 70 parts of sodium tungstate (Na2WO4.2H2O) in 150 parts of water and then add 6.4 parts sulfuric acid (HaSOi sp.gr.l.83) preferably stirring the solution while the acid is being added. Addition of the acid forms a yellow precipitate of tungstic acid which dissolves completely as sodium meta-tungstate whose formation is quickened by the stirring. 'Ihere is then added 1 part of formalin (40% HCHO in water). Parts given are by weight.

Solution No. 3 has a hardening or tanning action on the gelatin. By reason of the presence of sodium meta-tungstate (sodium tungstate is also present) a more stable precipitate is obtained when the sensitized gelatin is developed chemically and staining of the medium is prevented. The developed portions are therefore more resistant to light, heat and oxidation.

The hardening action is slow and will not seriously affect the viscosity of the solution for about an hour. It is preferred, however, to add the hardeningsolution just before coating the base layer I0.

The paper stock I is coated with the gelatinmercurous chloride colloid solution as indicated at I I by dipping, whirling or by any of the commercial coating machines. Machine coating is most satisfactory since a coating of uniform thickness is thus obtained. A satisfactory thickness of coating when dry is about 0.0025 of an inch.

Other sensitive coatings may be utilized in place of the mercurous chloride sensitized coating. For example, I may use a gelatin-silver chloride colloid solution which may be prepared substance.

in the same manner as herein above described for the preparation of the gelatin-mercurous chloride colloid solution and be usedas a coating solution in the same way. In this example solution No. l consists of 1000 parts water 1,00 `parts gelatin (dry). and

' '8 parts sodium chloride (NaCl) Solution No. 2 consists of:

v400 parts water and preparation ofthe 'gelatin-mercurous chloride colloid solution 'since the same temperatures, order of mixing andl manner of coating the paper stock may be utilized.

Again, instead of preparing a colloid solution as described hereinabove as a coating for the paper stock, I may employ ordinary photographic printing out paper as a base. Any of the silver papers of the gelatin emulsion type Whether chloride, iodide or bromide is suitable. I'hese papers are sensitive to light and to adapt them to my purpose they are first dissensltized. This is accomplished by exposing them to light and subsequently developing and fixing them in the ordinary manner. The blackened paper -ls then immersed in a. solution of mercurio chloride (HgClz) which bleaches it pure white. The silver remains in the gelatin as insoluble silver mercurous chloride .which is practically insensitive to light. 'I'he sheet isvwashed in running water to remove the excess mercurio chloride and dried, and there is obtaineda sensitized chemically developable sheet. I0.

To the coated paper stock or to the silver paper prepared as setforth above I then apply a very thin film I2 ofa gum or resinous-material. A film I3 of transparent orv translucent varnish insoluble in and impenetrable by the developers hereinafter described and water-proof where required is nextA applied to the film of gum or resin. 'I'he varnish film may be applied by printing and has a multiplicity of small spaced openings I4, shownv greatly enlarged in the drawing, through whichv the gum or resinous film is exposed. In the drawing circular openings are shown but it is clear that they may take any desired form. While a pattern of geometrically spaced openings is shown, my invention obviously is not limited to such a pattern. The openings may be in the formv of lines but whatever their shape they delineate areas or units which are accessible through the varnish print.

The use of the gum or resinous film is a feature of my media. By its employment I secure a much more solid print of the varnish film which having an oil base has Va greater affinity for a gum or a resinous substance than for a glutinous The gum or resinous film must be soluble in or penetrable by the hereinafter described developers which I utilize. These developers being alkaline solutions and the gum film being applied very thin a number of gum-resins and resins are available which will supply the desired printing surface and yet be soluble in the developer solutions.- Gum benzoin, ammoniac, sandarac, galbanum, olibanum, mastic, copal and dammar are satisfactory. I have-found a mixture of gum benzoin and ammoniac prepared as a spirit extract very effective." In its preparation I. add t0 400 milliliters of ethylene glycol monoethylether grams of 4gum benzoin (Sumatra, powder) and 5 grams of gumammoniac (powder). I let this stand for `about twenty-four hours, filter and discard the residue which con- 5 tains the dirt and insoluble matter in the gum. Purified gum extract may be used instead. The

sensitized gelatin film is coated with the filtrate when dry, a satisfactory drawing surface and aids the varnish print in resisting erasure.

A satisfactory surface coating'is supplied by a solution of 100 parts of 20% gum mastic in ethyl alcohol, 100 parts of 20% gum dammar in ethyl alcohol andparts of water. Parts are by weight. A coating of this solution may be ap. 25.plied by a whirler type coating machine. By

,reason of the presence of water which remains temporarily after the alcohol has evaporated the surface coating dries du1l,'translucent, and minutely porous satisfying the requirement of'a 30 desirable drawing suriace'fhaving the proper tooth. Although both-1 the gum mastic and gum dammar are practically insoluble in my hereinafter described developersthe porosityof the surface coating renders it readily penetrable 35 by the developers. Nearly all of the spirit soluble natural and synthetic resins and gums may be used in this manner.l A

I may also use water soluble gums in combination with spirit soluble gums and resins. One so- 40 lution may contain 50 parts by weight of 20% cherry gum in water and 50parts by weight of 20% gum galbanum in ethyl alcohol. The water solution of cherrygum is heated to boiling and the alcohol solution of gum galbanum is added 5 slowly with vigorous stirring. -".llhe gum galbanum being insoluble inthe water solution precipitates and is held in suspension by the viscous cherry gum. This solution is used as a surface coating in the same manner as the alcoholic gum l0 solution. It dries dull and is rendered penetrable by the presence of the water soluble cherry gum. The presence of the insoluble gum galbanum causes the solution to adhereto the surface of the media. Other water soluble substances such as gum arabic, gum tragacanth, soluble starch, dextrin, etc. may be used in place. of cherry gum. Any of the water insoluble resins and gums mentioned above may be substituted for the gum 60 galbanum.

While the hereinabove described surface coatings are quite satisfactory, I prefer to use a surface coating of 25% egg orblood albumen in H20. Application of this substance .may be made by a o whirl coater, roll coater or if desired lby dipping.

After application the substance is driedand then.

immersed for about one minutein a solution of 3% yumido or. sarbitol. in water at a. ternperature of approximately 190 F. The medium 70 is then dried. The yumidol and sarbitol which are non-drying viscous liquid plasticisers act to coagulate the albumen and to impart hardness and dullness thereto. The resulting surface coating is dull, transparentar translucent and 75 penetrable by-and insoluble in the developers emi i 3 ployed. The said coating, moreover, provides the required toot j In the employment of a medium in which numerous chloride is the sensitive substance I utilize an aqueous alkaline solution of .thiourea as the developing agent. lIn my preferred process of developmentlI use two developer solutions which I designate slow and fast developers. Characteristic of the slow developer, represented in Figs. 3 and 4 by the irregular closeduigure indicated by the numeral I8, is its quality of slowly enlarging the sensitized gelatim units accessible through the openings i4 in the varnish print I3. An even development of large `areas of lighter tone value is thereby secured and the work of the artist is facilitated. 4The fast developer is characterized by rapidity of enlargement, expansion or growth of these areas and is represented in Fig. 4 by the irregular closed figure designated by the numeral I1. In the use of both developers the expansion of the developed areas proceeds uniformly in all directions. The darker tone values are reachedwithout prolonged waiting. This quality of the fast developer together with other qualities hereinafter enumerated aid materially in the expeditious use of my media. To prepare my slow developer I mix by weight: v 100 lparts water 1.5 parts thiourea (NHzCSNI-Ia) parts sodium sulfate (NazSO The thiourea is the active agent in this developing solution. The sodium sulfate inhibits the diifusion of the solution into the gelatin.

In the preparation of my fast developer I mix by weight:

100 parts cold water 4 parts thiourea (NHzCSNHz) l 2 parts ethylenediamine 60% (NHzCI-IzCI-IzNHz) v0.4 parts phenolphthalein (CzoHi404) 15 parts urea (NI-I2.CO.NH2) 0.5 parts shellac in alcohol (commercial solution).

The thiourea is the active agent in the developmentof the mercurous chloride and in the presence of an alkali such as ethylenediamine effects precipitation of mercurio sulfide which is much blacker and more stable than the grey-black precipitate of metallic mercury obtained by thiourea alone. Ethylenediamine, moreover, causes the solution to diffuse more rapidly into the gelatin. Increased speed of diffusion is also secured by the urea whose use is preferred to a stronger concentration of ethylenediamine because of ,its noncaustic character.

As indicated above the vdeveloper solution Ais alkaline and it has a pH value of about 11. YThe presence of an indicator, e. g., phenolphthalein or o-cresolphthalein, therefore causes the solution to be dark red. in color.l Consequently, in the application of the developer, as by means of a brush, the artist can more easily follow his brush strokes, especially -over areas previously developed. Moreover, the fastdeveloper possesses a.

tenacity which inhibits spreading or creeping so that there is obtained a sharp definition of the surface to which said developer is applied.

The red color of the developer solution being nonactinic cannot be permitted to remain on the finished figure, design or drawing. -I-Iowever, the color fades automatically as the solution dries and becomes wholly colorless with complete drying. When completely dry thev pH value of the solution has dropped below 8.3, the color change colorless original key drawing, figure or design. More- I can replace the ethylenediamine of the developer solution by piperidine. Similarly, ammonium hydroxide, monoethanolamine, benzylamine, propylenediamine, alkali hydroxides such as sodium, potassium and lithium hydroxides and alkali salts such as sodium carbonate, borate and tri-phosphate vmay be substituted for ethylenediamine. Almost any water soluble alkaline substance which will produce a solution having a pH value greater than 8 .3 can be substituted for the ethylenuiiamine.

Where a gelatin-silver chloride colloid film or photographic "printing-out paper is employed sodium sulphite may be used as the developer.

Other reducing agents such as stannous chloride' sodium hydroxide or other alkalies; ethylenediamine or other alkaline amines; or combinations of these may also be used as developers.

All of the elements of my hereinabove described media with the exception of the base sheet are transparent or translucent. My invention contemplates the use of transparent or translucent base sheets in place of the opaque base sheet so that the media will be entirely transparent or translucent. Transparent sheets of cellulose acetate may be used. Other transparent or translucent materials such as cellulose nitrate, Celluloid, or other plastics, transparentized cloth or paper, glass, etc. may also be utilized.

The field of utility of my media is thereby greatly enhanced. Figures, designs, drawings and the like may be developed directly from copy placed under the media. Of particular importance is the use of my transparent or translucent media in the production of copy for color plates where such copy can be drawn to register by tracing the individual copies to register with an over, developed transparent or translucent media may be used as photographic negatives. 'Ihe developed portions are suiilciently opaque to resist the passage of light while the undeveloped portions oiIer little or no resistance thereto.

As indicated hereinabove the preferred manner of applying my developer solutions is by means of a brush. The action` of the solutions may be readily and effectively terminated by blotting up the excess of solution.

While I have disclosed my preference for the use of both the"slow and fast developers together, I do not intend to limit myself to such use. Obviously, either solution may be used alone to effect complete development of gradations of tone values having regard to the stated characteristics of these solutions. On the same medium the "fast" developer may be applied clirectly over the slow developer or. the slow developer may be applied to one part of the medium and the fast developer to another part. Nor do I intend to convey the idea that my developers are limited in their application to a medium having the specific structure'shown in Fig. 1 of the drawing. For example, these developers could be applied to a medium having a gelatin lm coated with the sensitive substance first described or from which the gum film or surface coating or both are absent. I comprehend within the purview of my invention all variations apparent to those skilled in the art and my said invention is not to be limited except as required bythe appended claims.

I claim:

1. As an article of manufacture a medium adapted for the preparation of figures, designs, drawings and the like. suitable for use as camera copy, comprising a base sheet, a gelatinous coating on said sheet containing chemically developable substance in suspension, a thin transparent or translucent lm o! gum or resinous substance soluble in or penetrable by the developers for said chemically developable substance on said coating, a coating of transparent or translucent material insoluble in and impenetrable by said developers on said film, said material having a multiplicity of spaced openings and a surface coating of dull, transparent or Vtranslucent material insoluble in and penetrable by said developers.

2. As an article of manufacture a medium adapted for .the preparation of figures. designs, drawings and the like, suitable for use as camera. copy. comprising a base sheet, a gelatinous coating on said sheet containing chemically developable mercurous chloride in suspension, a thin transparent or translucent film-of gum or resinous substance soluble in or penetrable by the developers for said chemically developable substance on said coating, a coating of transparent or translucent material insoluble in and impenetrable by said developers on said film, said material. having a multiplicity of spaced openings and a surface coating of dull transparent or translucent material insoluble in and penetrable by said developers.

3. As an article of manufacture a medium adapted for the preparation of gures, designs, drawings and the like, suitable for use as camera copy. comprising a base sheet, a gelatlnous coating on said sheet containing chemically developable substance in suspension, a thin transparent or translucent fllm of gum or resinous substance soluble in or penetrable by the developers for said chemically developable substance on said coating and a. coating of transparent or translucent material insoluble in and impenetrable by said developers on said film, said material having a multiplicity of spaced openings.

4. As an article of manufacture a medium adapted for the preparation of' figures, designs, drawings and the like, suitable for use as camera copy, comprising a base sheet, a gelatinous coating on said sheet containing chemically developable substance in suspension, a film of transparent or translucent material insoluble in and impenetrable by the developers for said chemically vdevelopable substance, said material having a multiplicity of spaced openings and a surface coating of dull transparent or translucent material insoluble in and penetrable by said developers.

5. The method of preparing figures, designs, drawings and the like upon, a medium bearing a chemically developable substance portions of which are accessible through a multiplicity of spaced openings in a transparent or translucent coating insoluble in and impenetrable by the developers for said substance comprising applying a slow-acting developer to said portions to ldevelop visible areas and applying a quick-actingl developer to said portions to expand said visible velopers for said substance comprising applying a. developer to said medium to develop a multiplicity of visible areas and applying a more rapidly acting developer to certain of said visible areas to expand said areas.

'1. The method of preparing figures, designs, drawings and the like upon a medium bearing a chemically developable mercurous compound accessible through a multiplicity of spaced openings in a transparent or translucent coating insoluble in and impenetrable by the developers for said compound comprising applying a developer containing thiourea and sodium sulphate to said compound through said openings to develop 1,5 visible areas and applying a developer containing thiourea and an alkaline substance to said compound through said openings to expand said visible areas.

8. The method of preparing iigures, designs,

drawings and the like upon a medium bearing chemically developable mercurous compound accessible through a muliplieity of spaced openings in a transparent or translucent coating insoluble in and impenetrable by the developers for said compound comprising applying a developer containing thiourea and sodium sulphate to said compound through said openings to develop visible areas and applying a developer containing thiourea, an alkaline substance and an alkaline indicator and having an initial pH value greater than 8.3 to said visible areas through said openings to expand said visible areas.

9. 'I'he method of preparing figures, designs,

drawings and the like upon a medium bearing a chemically developable substance covered by a thin transparent or translucent gum of resinous lm, areas of said substance being accessible for development through a. multiplicity of spaced 40 openings in a transparent or translucent coating insoluble in and impenetrable by the develop'er for said compound comprising applying a solvent-developer to said medium to dissolve said lm and render said areas visible.

l 10. The method of preparing figures, designs, y

drawings and the like upon a medium bearing a chemically developable substance covered by a thin transparent or translucent gum or resinous lm, portions of said substance being accessible for development through-a multiplicty of spaced openings in a transparent or translucent coating insoluble in and impenetrable by the developers for said'compound comprising applying .a solvent-developer to said medium to dissolve said i'llm and develop visible areas'and applying a. more quickly acting developer to said medium to expand said visible areas.

1l. The method of preparing figures, designs, drawings and the like upon a medium bearing a chemically developable substance covered by a thin transparent or translucent gum or resinous coating, portions of said substance being accessible for development through a multiplicity of spaced openings in a transparent or translucent coating insoluble in and impenetrable by the developer for said compound covered by a dull transparent or translucent lm insoluble in and penetrable by said developer comprising applying a solvent-developer to said medium so as to penetrate said lm, dissolve said gum or resinous coating and develop said portions into visible areas.

12. The method of preparing iigures, designs, drawings and the like upon a medium bearing a chemically developable substance covered by a thin transparent or translucent gum or resinous coating, portions of said substance being accessible for development through a multiplicity of spaced openings in a transparent or translucent coating insoluble in and impenetrable by l5 the developers for said compound covered by a dull transparent or translucent nlm insoluble in and penetrable by said developers comprising applying a solvent-developer to said medium so as to penetrate said film. dissolve said gum l0 or resinous coating and develop said portions into visible areas, and applying a more quickly acting developer to said medium so as to penetrate said illmand expand said visible areas.

13. As an article of manufacture a medium '15 adapted for the preparation of figures, designs, drawings and the like, suitable for use ascamera copy, comprising a base sheet bearing a chemically developable substance, said substance having applied thereto a thin transparent or trans- 20 lucent lm of gum or resinous material soluble in or penetrable by the developers for said chemically developable substance and a coating of a transparent or translucent substance insoluble in and impenetrable by said developers applied 25 to said film, said coating having a multiplicity of spaced openings.

14. As an article of manufacture a medium adapted for the preparation of figures, designs, drawings and the like, suitable for use as camera 30 copy, comprisingv a base sheet bearing a chemically developable substance, said substance having applied thereto a thin transparent or translucent iilm of gum or resinous substance soluble in or penetrable by the developers for said chem- 35 ically developable substance, a coating of a transparent or translucent substance insoluble in and impenetrable by said developers applied to said iilm, said coating having a multiplicity of spaced openings, and a coating of a dull transparent or 40 translucent material insoluble in and penetrable by said developers applied to said first mentioned coating.

15. As an article of manufacture a medium adapted for the preparation of figures, designs. drawings and the like, suitable for use as camera copy, comprising a base sheet bearing a chemically developable substance, Va nlm of a transparent or translucent substance insoluble in and 50 impenetrable by the developers for said substance, said film having a multiplicity of spaced openings and a filmof a dull transparent or translucent material insoluble in and penetrable by said developers applied to said first-mentioned 55 lm.

16. As an article of manufacture a medium adapted for the preparation of figures, designs, drawings and the like, suitable for use as camera copy, comprising a transparent or translucent 60 base sheet, a gelatinous coating on said sheet containing chemically developable substance in suspension, a thin transparent or translucent iilm of gum or resinous substance soluble in or penetrable by the developers for said chemically 65 developable substance on said coating, a coating of transparent or translucent material insoluble in and impenetrable by said developers on said i'llm, said material having a multiplicity of spaced openings and a surface coating of dull trans- 70 parent or translucent material insoluble in and penetrable by said developers.

17. The method of preparing figures, designs, drawings and the like upon a medium bearing a chemically developable substance portions of 75 which are accessible through a multiplicity of spaced openings in a transparent or translucent coating insoluble in and impenetrable by the developers for said substance comprising applying a slow-actingdeveloper to some of said portions to develop visible areas and applying a quickacting developer to other portions to develop larger visible areas.

18. As an article of manufacture a medium adapted for the preparation of gures, designs. drawings and the like suitable for use as camera copy, comprising a transparent or translucent base sheet, a .gelatinous coating on said sheet containing chemically developable substance, a coating of transparent or translucent material insoluble in and impenetrable by the developers for said chemically developable substance, said material having a multiplicity oi spaced openings and a surface of dull, transparent or translucent material insoluble in and penetrable by said developers.

19. As an article of manufacture a medium adapted for the preparation of ilgures, designs, drawings and the likesuitable for use as camera copy, comprising a transparent or translucent basell sheet, a gelatinous coating on said sheet containing chemically developable substance, a thin transparent or translucent film of gum or resinous substance soluble in or penetrable by the developers for said chemically developable substance on said coating and a coating of transparent or translucent material insoluble in and impenetrable by said developers on said nlm. said material having a\multiplicity of spaced openings.

20. As an article of manufacture a medium adapted for the preparation of figures, designs, drawings and the like suitable for use as camera copy, comprising a transparent or translucent base sheet, a gelatinous coating on said sheet containing chemically developable substance. and a coating of transparent or translucent material insoluble in and impenetrable by the developers for said chemically developable substance, said material having a multiplicity of spaced openings.

MAURICE D. MCINTOSH. 

